<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script type="text/javascript">
    var a = [1, 2];
    var b = a;

    b.push(3);

    console.log(b); // [1, 2, 3]


    console.log(a); // [1,2,3]

</script>

</html>
